Such a connector is known from U.S. Pat. No. 4,571,014. The known connector comprises several shielding elements of different shape. One of the known shielding elements has a square wave shape which has such dimensions that it encompasses all contact holes. However, neighboring contact elements within contact holes of adjacent rows of contact holes are not shielded from each other by the square wave shaped shielding element. To solve this problem, in the known connector additional shielding plates are applied which are arranged in such way as to shield neighboring contact elements of adjacent rows. These additional shielding plates are provided with appropriate slots to receive the square wave shaped shielding element in order to provide such an entire shielding structure that each contact element is shielded from any neighboring contact element. However, such a combination of shielding elements is complex and the manufacturing of such a connector is complicated.
European patent application 0,074,205 discloses a connector for connecting conductors of coaxially shielded cables to contact pins arranged in one row on a board. Each shielded cable has an external ground terminal of rectangular shape. The contact pins on the board are surrounded by one square-wave shaped contact element, which is shaped in such a way that each "square wave" part may receive one external ground terminal of a shielded cable. No connector having contact holes comprising contact elements and arranged in at least two columns and at least two rows are shown or described. Furthermore, since the external ground terminal of each cable has to be inserted in a "square wave" part of the square wave shaped contact element the dimensions of each of the "square wave" parts are larger than of the outer ground terminals of the cables. This counteracts a design with minimum dimensions.
Further prior art shielding elements may be derived from European patent applications 0,446,980 and 0,337,634 and from U.S. Pat. No. 4,632,476.
Connectors of the type mentioned above are used, for example, for connecting a large number of signal wires to a printed circuit board. To this end, the connector is provided with a number of columns of contact holes with contact members disposed therein, two signal connections and one ground connection being effected, for example, in each column of contact members thus formed. For the purpose of some applications it may be advantageous, however, to form columns of five or more contact holes with contact members disposed therein. Since it is preferable, for example for forming connections to a printed circuit board, to use as small a number of connectors as possible for this purpose, it will often be the case that many signal connections, for example several tens of connectors, are made in one connector. As miniaturization becomes more prevalent, on the one hand, the number of signal wires to be connected to a connector increases, while on the other hand the dimensions of the connector itself must not increase and preferably should even decrease. This results in an increasing number of signal and ground connections in the limited space of the connector. In the case of high-frequency applications, this results inter alia in the risk of cross talk due to mutual electromagnetic interference of the signal connections.